1. Field of the Invention
The present invention generally relates to infrared radiation detecting devices as well as methods and apparatuses for manufacturing infrared radiation detecting devices. More specifically, the present invention relates to infrared radiation detecting devices with improved infrared radiation absorptance characteristics as well as methods and apparatuses for manufacturing infrared radiation detecting devices with improved infrared radiation absorptance characteristics.
2. Background Information
There are many different types of infrared radiation detecting devices that are currently available. One type of infrared radiation detecting devices is a thermal type of infrared radiation sensor that utilizes a change in the physical properties of the device when the temperature of the device rises by absorbed infrared radiation. In other words, thermal types of infrared radiation sensors are capable of detecting a heat radiation source by examining the temperature distribution in a space to be measured.
An example of a thermal infrared radiation sensor is a thermopile infrared radiation sensor that detects a thermal electromotive force developed between metals. In particular, the thermopile infrared radiation sensor utilizes one or more thermocouples in which a thermal electromotive force is generated by a temperature difference between hot and cold junctions of the thermocouples. A thermopile infrared radiation sensor typically includes a substrate, at least one thermocouple formed above the substrate, and a suspending membrane. There are many different constructions of thermopile infrared radiation sensors.
In constructing infrared radiation detecting device such as thermopile infrared radiation sensors, a gold black film is often deposited on the substrate by vapor deposition to serve as an infrared radiation absorbing film. Establishing the order of the processing steps and the atmosphere to be used has been one issue when depositing the gold black film onto the substrate by vapor deposition to form the infrared radiation absorbing film. In response to this issue, the idea of mixing particles of gold black, carbon, or other substance that absorbs infrared radiation into a transparent, resin-light liquid carrier material and forming the infrared radiation absorbing film on the substrate using an inkjet method has been proposed. An example of such a conventional infrared radiation detecting device and method of manufacturing such an infrared radiation detecting device is disclosed in Japanese Laid-Open Patent Publication No. 2000-340848. With the conventional technology disclosed in this Japanese Publication, a resin film containing particles of gold black, carbon, or other substance that absorbs infrared radiation is simply deposited onto the substrate in an even manner using an inkjet method to form the infrared radiation absorbing film.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an infrared radiation detecting device with improved infrared radiation absorptance characteristics as well as methods and apparatuses for manufacturing such an improved infrared radiation detecting device. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.
It has been discovered that the surface reflectance of the infrared radiation absorbing film of an infrared radiation detecting device that has been constructed in accordance with the above-mentioned conventional technology cannot be lowered. Thus, the infrared radiation absorptance reflectance of the infrared radiation absorbing film of an infrared radiation detecting device that has been constructed in accordance with the above-mentioned conventional technology cannot be improved.
One object of the present invention is to provide an infrared radiation detecting device, as well as a manufacturing method and manufacturing apparatus for the same, in which the infrared radiation absorptance of the infrared radiation absorbing film can be increased.
The aforementioned object can basically be attained by providing an infrared radiation detecting element comprising an infrared radiation absorbing film constructed to convert incident infrared radiation with a intensity and a predetermined wavelength into thermal energy, and detect the intensity of the incident infrared radiation. The infrared radiation absorbing film has a plurality of thick points with first film thicknesses arranged in a predetermined pattern relative to a plurality of thin points with second film thicknesses. The thick and thin points are configured and arranged such that a predetermined film thickness difference is formed between the thick and thin points and a predetermined spacing within a plane is formed between the thick points. The predetermined spacing and the predetermined film thickness difference are arranged and configured to decrease effective surface reflectance due to interference or scattering of the incident infrared radiation striking the infrared radiation absorbing film.
These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention.